William burnett



Patent 51,279.

THE RECORDS OF THE OFFICE SHOW TI-Ii ABOW DRAWING AS BEIHG LOST ORBESTROYED WEE "UNITED STATES PATENT @FFICE,

WILLIAM BURNE'ITT, OF BOSTON, MASQACHUSET'IS, ASSIGNOR TO ROBERTBURNETT, OF NEW' YORK, N. Y.

STEAM-PRESSURE GAGE.

Specification of Letters Patent No. 31,279, dated January 29, 1861.

To all whom it may concern:

Be it known that I, XVILLIAM BURNETT, of Boston, in the county ofSuffolk and State of Massachusetts, have invented a new and ImprovedPressure Gage or Indicator; and I do hereby declare that the followingis a full and exact description thereof, reference being had to theaccompanying drawing, making part of this specification, and to lettersof reference marked thereon.

The nature of my invention consists in certain improvements in the modeof deriving motion from elastic metallic plates or disks, or otherelastic substances which may be employed in such gages or indicators asan elastic medium upon which the pressure to be measured acts,whereby anincreased first motion is secured, far greater than that which may beobtained by simply employing as a first movement, the direct motionproduced by the bulging out of one side of the plate or disk whenpressure is applied to the other. \Vhen the simple bulging of such aplate or disk, on being subjected to pressure, is relied on as a firstmotion in such indicators, it will be quite apparent that any littlewear of the parts employed to increase the motion, in communicating thesame to a suitable index, must very seriously affect the truthfulness ofits indications; to obviate this difficulty, as well as to avoid thenecessity of requiring so large a movement in the disk itself, asheretofore found necessary, are some of the objects of this invent-ion.

To enable others skilled in the art to make and use my invention, I willproceed to describe its construction and operation, reference being hadto the accompanying drawing. To a circular metallic case (A Figure l)forming a chamber of suitable depth to receive the working parts, isattached a second chamber (B) opening into the first,this latter chamberbeing intersected by a circular elastic plate or diaphragm (C) uponwhich the pressure acts, the pressure being admitted through a pipe (D)into that portion of the chamber below the elastic plate. One end of arigid arm or bar is firmly secured to the elastic plate or disk (C),while the other end of said arm or bar is left free to move laterally,for the purpose of drivingv a sector by means of a link (G), whichcauses the said sector to revolve a pinion (E) into which it is geared,thereby communicating motion through its shaft, to an arrow or pointer(J) employed to indicate the pressure upon the dial. The fixed end ofthe arm or bar E) is not, it will be perceived, attached to the centerof the plate (C), for in that case, on pressure being applied under theplate, no lateral motion of the bar would ensue, but the said bar isrigidly connected with the elastic plate at some distance from itscenter or point of greatest direct motion, and at that part of itssurface which assumes, when pressure is admitted beneath the plate, thesteepest angle when considered relatively to the plane represented bythe surface of the plate when in a state of rest. 7

I do not confine myself to the precise arrangement of parts abovedescribed, but have merely given this example as an illustration inwhich the principle of my invention is embodied; nor is my inventionconfined to the attachment of a single rigid arm, such as thatdescribed, to a point removed from the center of greatest motion of aflat circular elastic plate, as obviously, two such arms may beemployed, the same being affixed to the elastic plate soas to movelaterally-in opposite directions, by being secured to the said plate atopposite sides of its center, and their combined motion employed,through suitable mechanism, to indicate the pressure ;or the elasticplate may be of any other form, and may be corrugated either in straightlines or in concentric circles, without changing the principle ofaction; and the arm employed may also have a different positionrelatively to the surface upon which it is affixed, and may lie parallelthereto,-as shown at Fig. 2 of the drawings, in which, as abovedescribed, the bar is represented as lying parallel to the elastic plate(C) ,the dotted lines show ing the position of the parts when subjectedto pressure; or,as shown at Fig. 3, of the drawings, said arm or bar maybe affixed to the side of a short flattened tube (C), or a tube of whichthe transverse sec tion is elliptical, in such a position that a lateralmotion of the free end of the arm will ensue upon the application ofpressure to the interior of the tube,this would also embody theprinciple of myinvention. I intend also to employ this instrument as avacuum gage, and as a barometer ;in the latter case the air must beremoved from the direct motion, and in such a position that a lateralmotion of the free end of said bar or arm is induced, and employed,through suitable mechanism, to indicate the pressure, 15

substantially in the manner and for the purpose herein specified.

WM. BURNETT.

WVitnesses ROBERT B. HINE, v W. S. CLARY.

